Re: [PATCH v2 3/3] mm/mempolicy: introduce MPOL_WEIGHTED_INTERLEAVE for weighted interleaving

From: Gregory Price <gregory.price@memverge.com>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Gregory Price <gourry.memverge@gmail.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-api@vger.kernel.org, corbet@lwn.net,
	akpm@linux-foundation.org, honggyu.kim@sk.com, rakie.kim@sk.com,
	hyeongtak.ji@sk.com, mhocko@kernel.org, vtavarespetr@micron.com,
	jgroves@micron.com, ravis.opensrc@micron.com,
	sthanneeru@micron.com, emirakhur@micron.com, Hasan.Maruf@amd.com,
	seungjun.ha@samsung.com, hannes@cmpxchg.org,
	dan.j.williams@intel.com,
	Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com>
Subject: Re: [PATCH v2 3/3] mm/mempolicy: introduce MPOL_WEIGHTED_INTERLEAVE for weighted interleaving
Date: Tue, 23 Jan 2024 00:16:12 -0500	[thread overview]
Message-ID: <Za9LnN59SBWwdFdW@memverge.com> (raw)
In-Reply-To: <Za9GiqsZtcfKXc5m@memverge.com>

On Mon, Jan 22, 2024 at 11:54:34PM -0500, Gregory Price wrote:
> > 
> > Can the above code be simplified as something like below?
> > 
> >         resume_node = prev_node;
---         resume_weight = 0;
+++         resume_weight = weights[node];
> >         for (...) {
> >                 ...
> >         }
> > 
> 
> I'll take another look at it, but this logic is annoying because of the
> corner case:  me->il_prev can be NUMA_NO_NODE or an actual numa node.
> 

After a quick look, as long as no one objects to (me->il_prev) remaining
NUMA_NO_NODE while having a weight assigned to pol->wil.cur_weight, then
this looks like it can be simplified as above.

I don't think it's harmful, but i'll have to take a quick look at what
happens on rebind to make sure we don't have a stale weight.

~Gregory